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Anionic cascade reactions. One-pot assembly of (Z)-chloro-exo-methylenetetrahydrofurans from ?-hydroxyketones.

ABSTRACT: The assembly of (Z)-chloro-exo-methylenetetrahydrofurans by an original and connective anionic cascade sequence is reported. Base-catalysed condensation of ?-hydroxyketones with 1,1-dichloroethylene generates, in moderate to good yields, the corresponding (Z)-chloro-exo-methylenetetrahydrofurans. Acidic treatment of this motif leads to several unexpected dimers, possessing unique structural features.

SUBMITTER: Marko IE

PROVIDER: S-EPMC3701418 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Anionic cascade reactions. One-pot assembly of (Z)-chloro-exo-methylenetetrahydrofurans from β-hydroxyketones.

Markó István E IE Schevenels Florian T FT

Beilstein journal of organic chemistry 20130703

The assembly of (Z)-chloro-exo-methylenetetrahydrofurans by an original and connective anionic cascade sequence is reported. Base-catalysed condensation of β-hydroxyketones with 1,1-dichloroethylene generates, in moderate to good yields, the corresponding (Z)-chloro-exo-methylenetetrahydrofurans. Acidic treatment of this motif leads to several unexpected dimers, possessing unique structural features. ...[more]

PMID: 23843927

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Project description:Glycosylation of proteins is a key function of the biosynthetic-secretory pathway in the endoplasmic reticulum (ER) and Golgi apparatus. Glycosylated proteins play a crucial role in cell trafficking and signaling, cell-cell adhesion, blood-group antigenicity, and immune response. In addition, the glycosylation of proteins is an important parameter in the optimization of many glycoprotein-based drugs such as monoclonal antibodies. In vitro glycoengineering of proteins requires glycosyltransferases as well as expensive nucleotide sugars. Here, we present a designed pathway consisting of five enzymes, glucokinase (Glk), phosphomannomutase (ManB), mannose-1-phosphate-guanyltransferase (ManC), inorganic pyrophosphatase (PmPpA), and 1-domain polyphosphate kinase 2 (1D-Ppk2) expressed in E. coli for the cell-free production and regeneration of GDP-mannose from mannose and polyphosphate with catalytic amounts of GDP and ADP. It was shown that GDP-mannose is produced at various conditions, that is pH 7-8, temperature 25-35°C and co-factor concentrations of 5-20?mM MgCl2 . The maximum reaction rate of GDP-mannose achieved was 2.7??M/min at 30°C and 10?mM MgCl2 producing 566?nmol GDP-mannose after a reaction time of 240?min. With respect to the initial GDP concentration (0.8?mM) this is equivalent to a yield of 71%. Additionally, the cascade was coupled to purified, transmembrane-deleted Alg1 (ALG1?TM), the first mannosyltransferase in the ER-associated lipid-linked oligosaccharide (LLO) assembly. Thereby, in a one-pot reaction, phytanyl-PP-(GlcNAc)2 -Man1 was produced with efficient nucleotide sugar regeneration for the first time. Phytanyl-PP-(GlcNAc)2 -Man1 can serve as a substrate for the synthesis of LLO for the cell-free in vitro glycosylation of proteins. A high-performance anion exchange chromatography method with UV and conductivity detection (HPAEC-UV/CD) assay was optimized and validated to determine the enzyme kinetics. The established kinetic model enabled the optimization of the GDP-mannose regenerating cascade and can further be used to study coupling of the GDP-mannose cascade with glycosyltransferases. Overall, the study envisages a first step towards the development of a platform for the cell-free production of LLOs as precursors for in vitro glycoengineering of proteins.

Dataset Information

Anionic cascade reactions. One-pot assembly of (Z)-chloro-exo-methylenetetrahydrofurans from ?-hydroxyketones.

Publications

Anionic cascade reactions. One-pot assembly of (Z)-chloro-exo-methylenetetrahydrofurans from β-hydroxyketones.

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